1. Field of Invention
The present invention relates to a method and apparatus that produces a color filter used for optical devices, such as a liquid crystal device, and the like. The present invention also relates to a method and apparatus to manufacture a liquid crystal device having a color filter. The present invention further relates to a method and apparatus to manufacture an EL device that displays by using an EL luminescent layer. The present invention further relates to a method of discharging a material to an object, and an apparatus that controls a head. The present invention further relates to an electronic apparatus having a liquid crystal device or an EL device manufactured by the above-described method.
2. Description of Related Art
Recently, display devices, such as a liquid crystal device, an EL device, and the like have been widely used as display sections of electronic apparatuses, such as cell phones, portable computers, etc. Also, in recent years, full-color displays using a display device have been increasingly made. A full-color display of a liquid crystal device is made by, for example, transmitting light, which is modulated by a liquid crystal layer, through a color filter. The color filter includes dot-shaped color filter elements of R (red), G (green) and B (blue), which are formed in a predetermined arrangement such as a stripe, delta, or mosaic arrangement on the surface of a substrate of glass, plastic, or the like.
In a full-color display of an EL device, dot-shaped EL luminescent layers of R (red), G (green) and B (blue) colors are provided in a predetermined arrangement on electrodes, which are formed in any desired arrangement, for example, a stripe, delta, or mosaic arrangement, on the surface of a substrate made of, for example, glass, plastic, or the like. The voltage applied to these electrodes is controlled for each pixel to emit light of a desired color from each pixel, thereby performing a full-color display.
In the related art, it is known that a photolithography process is used to pattern the filter elements of each of the R, G, and B colors of the color filter, or to pattern the pixels of each of the R, G, and B colors of the EL device. However, the use of the photolithography process has complicates the process, and increases the cost due to the high consumption of each color material and photoresist, etc.
In order to solve the problems, a method has been proposed in which a filter material, an EL luminescent material, or the like is discharged in a dot shape to form a dot-arrangement filter element or EL luminescent layer, or the like.
Consideration will now be given to a case in which, as shown in FIG. 23(b), a plurality of dot-shaped filter elements 303 are formed by an ink jet method in each of a plurality of panel areas 302, which are set on the surface of a large-area substrate of glass, plastic, or the like, for example, a so-called motherboard 301 shown in FIG. 23(a).
In this case, during several times (twice in the case shown in FIG. 23) of main scanning with an ink jet head 306 having a nozzle row 305 including a plurality of nozzles 304 arranged in a row as shown in FIG. 23(c) for each panel area 302, as shown by arrows A1 and A2 in FIG. 23(b), a filter material, for example, ink, is selectively discharged from the plurality of nozzles to form the filter elements 303 at desired positions.
The filter elements 303 of each of the R, G, and B colors are formed in an appropriate arrangement such as a stripe, delta or mosaic arrangement. Therefore, for ink discharge from the ink jet head 306, the ink jet head 306 for discharging each of the R, G, and B colors is previously provided for each of the three colors R, G and B so that the ink jet heads 306 are successively used to form an arrangement of the three colors of R, G and B on the motherboard 301, as shown in FIG. 23(b).
The ink jet head 306 generally causes variations in the amounts of the ink discharged from the plurality of nozzles 304 which constitute the nozzle line 305. For example, the ink jet head 306 has such an ink discharge property Q that the discharge amounts at positions corresponding to both ends of the nozzle line 305 are large; the discharge amounts at intermediate positions between both ends and the center are small; the discharge amounts in the central portion of the nozzle line 305 are medium between both ends and the intermediate positions, as shown in FIG. 24(a).
Therefore, when the filter elements 303 are formed by the ink jet head 306 as shown in FIG. 23(b), dark stripes with a high density are formed at positions P1 corresponding to the ends of the ink jet head 306 or center P2, or both the positions P1 and the center P2, thereby causing nonuniformity in the planar light transmission property of the color filter, as shown in FIG. 24(b).
The present invention has been achieved in consideration of the above problem, and an object of the present invention is to provide a method and apparatus to produce each of optical members which are capable of making uniform in a plane the optical properties of an optical member, such as the distribution properties of light transmission of a color filter, the color display properties of a liquid crystal device, the luminescence properties of an EL luminescent plane, etc.
A method of producing a color filter of the present invention includes a first main scanning step of scanning, along a main scanning direction, one of a substrate and a head relative to the other, the head having a nozzle row including an arrangement of a plurality of nozzles, while discharging a filter material from the plurality of nozzles to the substrate, a second main scanning step of scanning one of the head and the substrate relative to the other along the main scanning direction while discharging a filter material to the substrate. In the second main scanning step, scanning is performed in such a manner that a portion of the crossing region of the nozzle row and the substrate overlaps with at least a portion the crossing region in the first main scanning step.
In the method of producing a color filter of the present invention, each of the filter elements of the color filter is formed to a predetermined thickness by repeatedly discharging ink from the plurality of nozzles, not by single scanning with the head. Therefore, even if there are variations in the amounts of the ink discharged from the plurality of nozzles, the occurrence of variations in thickness of the plurality of filter elements can be prevented, thereby making the distribution properties of light transmission of the color filter uniform in a plane.
Since the method of producing a color filter uses the head including the plurality of nozzles, of course, the method has no need to pass through such a complicated step as in a method including a photolithography process, and causes no waste of materials.
Also, in the method of producing a color filter, preferably, the first main scanning step is performed several times so that the crossing region of the nozzle row and the substrate in each performance of the main scanning step does not overlap with the crossing regions in the other performances of the main scanning steps. Namely, the entire surface of the substrate in a dry state can be set to a uniformly wet state with a uniform thickness before a filter material is repeatedly discharged several times to form the filter elements having the predetermined thickness, and thus marked boundaries can be prevented from remaining at the ink overlap boundaries in subsequent repeated coatings.
Not only the first main scanning step, but also the second main scanning step is performed several times so that the crossing region of the nozzle row and the substrate in each performance of the second main scanning step does not overlap with the crossing regions in the other times of the second main scanning steps.
In this method, each of the filter elements of the color filter is formed to a predetermined thickness by repeating several times the step of discharging the filter material to a uniform thickness on the surface of the substrate, not by single scanning with the head. Therefore, even if there are variations in the amounts of the ink discharged from the plurality of nozzles, the occurrence of variations in thickness of the plurality of filter elements can be prevented, thereby making the distribution properties of light transmission of the color filter uniform in a plane.
Furthermore, in this method, in the first performance of the main scanning step, i.e., in forming the filter material directly on the surface of the substrate, main scanning is performed to avoid overlapping of the nozzle row, and thus the filter material can be adhered in a uniform thickness to the entire surface of the substrate. Therefore, the entire surface of the substrate generally in a dry state can be set to a uniformly wet state with a uniform thickness, thereby preventing marked boundaries from remaining at the overlap boundaries of the filter material in subsequent repeated coatings.
The nozzle row is virtually divided into a plurality of groups, and in the second main scanning step, the crossing region of each of the groups and the substrate in the first main scanning step overlaps with the crossing region of at least one of the other groups and the substrate in the first main scanning step. The method of the present invention preferably further includes the sub-scanning step of scanning one of the head and the substrate relative to the other in a sub-scanning direction crossing the main scanning direction in such a manner that main scanning is repeated several times with sub-scanning movement by a length of an integral multiple of the length of each nozzle group in the sub-scanning direction. By using this construction, the plurality of the nozzle groups scan the same portion of the substrate to repeatedly supply the filter material to each of the filter element regions from the nozzles in each of the nozzle groups.
The nozzle row can be arranged at an angle with the sub-scanning direction. The nozzle row includes the plurality of the nozzles which are arranged in a row. In this case, when the nozzle row is arranged in parallel to the sub-scanning direction of the ink jet head, the distance between the adjacent filter elements formed by the filter element material discharged from the nozzles, i.e., the element pitch, equals to the nozzle pitch of the plurality of the nozzles of the nozzle row.
When the element pitch may be equal to the nozzle pitch, the nozzle row may be arranged in parallel to the sub-scanning direction. However, such a case is a rare case, and in many cases, the element pitch is generally different from the nozzle pitch. When the element pitch is different from the nozzle pitch, like in the above-described construction, the nozzle row is inclined from the sub-scanning direction so that the length of the nozzle pitch along the sub-scanning direction can be coincided with the element pitch. In this case, the position of each of the nozzles constituting the nozzle row is shifted forward or backward in the main scanning direction. However, ink droplets can be supplied to a desired position from each of the nozzles by shifting the timing of discharge of the filter material from each of the nozzles.
In the first and second methods of producing a color filter, the length of sub-scanning movement of the head can be determined as follows. Assuming that the length of the nozzle row is L, the number of the groups formed by dividing the nozzle row is n, and the angle formed by the nozzle row and the sub-scanning direction is xcex8, the length xcex4 of sub-scanning movement is as follows:
xcex4≈Integral multiple of (L/n)cos xcex8.
In this construction, the plurality of the nozzles of the head can be moved for each nozzle group in the sub-scanning direction. As a result, for example, considering the case in which the nozzle row is divided into four nozzle groups, each region of the substrate is repeatedly scanned by the four nozzle groups.
In the first and second methods of producing a color filter, a control method can be used, in which the filter material is not discharged from the nozzles present at both ends of the nozzle row. As described above with reference to FIG. 24(a), in a general head, the ink discharge distribution of either end portion of the nozzle row is different from the other portions. In an ink jet head having such an ink discharge distribution, a plurality of nozzles having a uniform ink discharge distribution, except some nozzles in either end portion of the nozzle row, which have great change in the discharge distribution, are used to make the thickness of the filter elements uniform in a plane.
Furthermore, in processing without using the nozzles present at both ends of the nozzle row, as described above, the length of sub-scanning movement of the head can be determined as follows. Assuming that the length of the nozzle row except the end portions, where ink is not discharged from the nozzles, is L, the number of the groups formed by dividing the nozzle row is n, and the angle formed by the nozzle row and the sub-scanning direction is xcex8, the length xcex4 of sub-scanning movement can be determined as follows:
xcex4≈Integral multiple of (L/n)cos xcex8.
The color filter produced by each of the first and second methods of producing a color filter generally includes the filter elements of plural colors including R (red), G (green), and B (blue), or C (cyan), M (magenta), and Y (yellow), which are arranged in an appropriate planar pattern. In producing the color filter that has such filter elements having plural colors, the first or second main scanning step is performed by using a plurality of the heads so that the filter materials discharged from the plurality of the heads have different colors, the first or second main scanning step being performed for each head.
In another embodiment of the method of producing a color filter having filter elements having plural colors, a head may be provided with a plurality of nozzle rows so that the nozzle rows discharge filter materials of different colors.
An apparatus to produce a color filter by arranging filter elements on a substrate according to the present invention includes a head including a nozzle row having a plurality of nozzles arranged in a row, first main scanning device to scan one of the head and the substrate relative to the other in a main scanning direction, and second main scanning device to scan one of the head and the substrate relative to the other along the main scanning direction, wherein the second main scanning device performs main scanning in such a manner that a portion of the crossing region of the nozzle row and the substrate in first main scanning overlaps with at least a portion of the crossing region in first main scanning.
The apparatus to produce a color filter preferably includes an ink supply device that supplies a filter material to the head, a sub-scanning device that moves the head in the sub-scanning direction crossing the main scanning direction, and a nozzle discharge control device to control ink discharge from the nozzle.
A method of manufacturing a liquid crystal device having a color filter formed on one of a pair of substrates, which hold a liquid crystal therebetween, according to the present invention includes the step of forming the color filter on the substrate by any one of the above-described methods of producing a color filter.
An apparatus for manufacturing a liquid crystal device of the present invention includes the above-described apparatus for producing a color filter as a component, particularly, a mechanism that produces a color filter.
A method of manufacturing an EL device of the present invention is described below. An EL device generally includes EL luminescent layers which are arranged in a dot arrangement on a substrate, and can thus be manufactured by the same as the above-described method of producing a color filter. Namely, the method of manufacturing an EL device of the present invention uses an EL luminescent material in place of the filter material used in the method of producing a color filter.
An apparatus to manufacture an EL device of the present invention can also be realized in the same manner as the apparatus that produces a color filter. In this case, of course, the material discharged from a head is the EL luminescent material.
Besides the color filter, the liquid crystal device, and the EL device, the present invention can also be applied to various industrial technical fields by appropriately changing a discharged material and a discharge object.
The liquid crystal device and the EL device manufactured by the method of manufacturing a liquid crystal device and the method of manufacturing an EL device of the present invention can be mainly used as display sections, and particularly used for electronic apparatuses such as personal computers, cell phones, portable information devices, etc.
A method of discharging a material of the present invention is a technique which can be used in a wide industrial application field, and an electronic component produced by using this method as a production step can also be used for electronic apparatuses, such as personal computers, cell phones, portable information devices, etc.